This invention relates to a valve, and more particularly to one-way and two-way valves which are particularly suited to low-pressure applications.
One-way poppet valves which function to admit a fluid into a system or allow a fluid to egress from a system are well known. These valves usually have a valve element consisting of a circular head mounted on an elongated shaft extending normally from the head and through a valve guide. The valve head seals against a cylindrical valve seat. The valve element is urged into a closed position wherein the head seals against the seat by a compression spring, and is opened by lifting the valve head from the seat by some form of mechanical action, or by a pressure differential across the valve.
Two-way valves which function to admit air or fluid into a system in response to negative pressure within the system and to release air or fluid from the system in response to positive pressure, are also common. Examples of such valves are disclosed in U.S. Pat. No. 507,636 which describes a two-way valve for use on beer tanks, U.S. Pat. No. 2,351,874 showing a two-way valve for use with fuel tanks, South African Patent 90/5617 on two-way float valves, and South African Patents 87/6659 and 89/8855 corresponding to U.S. Pat. No. 4,962,548 on a two-way valve for use with sanitary plumbing systems.
All of these two-way valves have a valve housing, a cross-plate within the housing, at least two apertures through the cross-plate and at least two one-way valve means arranged to seal the apertures, but operable to permit a bi-directional flow of fluid. These valves all utilize a closure member or diaphragm which is urged into a closed position by a compression spring.
The above described valves have a disadvantage because the valve mechanism is relatively complex involving many parts. This adds to the costs of each valve, as the parts must be fabricated and assembled to form the valve assembly. In addition, the diaphragm is slidable on a spindle which can wear. This can result in the diaphragm sticking in either an open position or a closed position.